There are many different piston shoes known in radial-piston type fluid-handling devices. These piston shoes have been of different structure and function. Most of them have operated satisfactorily in fluid-handling devices of certain pressures in the fluid in the devices.
It is also known to provide support means or guide means for the piston shoes of the prior art. Some piston shoes are already "entering piston shoes" which means that they enter at least partially into the fluid-handling body or cylinder-containing body of the device. However, as well as the best known piston shoes have operated at certain pressures in fluid, strokes in the device or speeds of the moving parts or power, size or efficiency of the known devices, they still have not obtained the maximum possible powers, efficiencies, pressures in fluid or rate of flow of fluid through the device of a given size or weight.
It is therefore another aim and object of this invention, to increase the power and/or efficiency of radial-piston devices without increasing their outer sizes or weights. It is the aim to increase at least the power to higher powers and/or efficiencies than those ever obtained in radial-piston fluid-handling devices of the known type.
It is also known to connect pistons and piston shoes so that the piston shoes can swing or pivot in the respective connection means of the pistons. In as far as these piston shoes can enter or deeply dive into the cylinder or fluid handling body of the device, they operate with large piston strokes and through flow or rate of flow of fluid through the device. However, in order to connect a piston shoe pivotally or swingably with a piston one or both has to embrace the other at least to a limited extent. Since otherwise the piston and piston shoe would not be connected together with an ability to swing or pivot relatively to each other or on each other. This embracing of one part by the other needs a certain portion of the cross-sectional area of at least one of the parts. It thereby limits the maximum cross-sectional area or bearing area of the bearing faces of the piston piston shoe swing or pivot connection of the piston and piston shoe assembly. Consequently in these piston piston-shoe assemblies only a fraction of the cross-sectional area of the piston could be utilized for the provision of a bearing means or bearing faces between the piston and piston shoe for bearing on each other. Another fraction of the cross-sectional area of the piston remains for the swing or pivot connection between the piston and piston shoe for the embracing of one of the parts by the other. Since accordingly in these known devices or piston piston shoe assemblies only a portion of fraction of the cross-sectional area of the piston can be utilized for the provision of a bearing or bearing faces on or between the piston and piston shoe, a piston piston-shoe assembly of this known kind can never obtain the same high pressure capability which a piston piston-shoe assembly can obtain where the whole or almost the whole cross-sectional area of the piston is utilized for the provision of the bearing means between the piston and piston shoe of the assembly.
It is therefore another aim and/or object of this invention, to provide a radial piston device which is capable of operating at higher fluid pressures because a bearing area is provided between the pistons and piston shoes of the device which is increased over the size of the known cross-sectional relative areas of bearing means of pivotal operating pistons and/or piston shoes of the prior art. Accordingly the bearing area or bearing face areas may be increased by this invention to extend almost or wholly over the whole cross-sectional area of the piston.
Some radial piston devices already use great cross-sectional areas for the bearing means between the pistons and piston shoes. However, in these devices the piston shoes extend beyond the cross-sectional area of the associated pistons. Thus they extend over the cross-sectional areas of the pistons and cylinders. Consequently they need for their motion and operation a special space which has to be wider than the diameter of the cylinders and pistons. These known arrangements therefore require either a shorter piston stroke in a device of the given size or they require a bigger diameter of the fluid-handling body for the provision of the required wider space. The latter necessitates a bigger diameter of the device and therefore an increase in its size and weight for a given size of piston stroke and thereby of rate of flow through the device. Both requirements result in any case in a device of a given size and weight in a reduction of the rate of flow of fluid through the device. The known wider bearing provisions of the art therefore resulted in a reduction of the rate flow capability of the devices. With the required restriction of the rate of flow through the device of a given size and weight these devices of the known type also restrict the power of the devices in a given size and weight.
It is also an aim and object of this invention not only to increase the cross-sectional area of the bearing faces between the piston and piston shoe, but also at the same time to obtain a high-pressure capability in a radial-piston type fluid-handling device of highest rate of flow or volumetric capacity at a given size and/or weight of the device. It is therefore the aim of the invention to obtain a high-pressure capability and at the same time and in the same device a high volumetric or flow through capability.
The radial piston devices of the prior art, which have piston shoes which are pivotally connected to the pistons are not easy to manufacture. They are complicated to machine and thereby also expensive. The known radial piston devices of the former type which have piston shoes of high bearing capacity extending beyond the diameter of the pistons and cylinders need space for their location and movement, which in turn has rotors of bigger diameters for a given piston stroke necessary. Thereby these devices become heavy, voluminous and big for a given piston stroke or flow through or volumetric capability. Thereby also these devices become expensive and complicated.
It is therefore a further aim and object of this invention to provide a radial piston device, which has the features of the other aims of the invention but which is in addition also easy to manufacture and inexpensive due to the small size and weight of material for a given power.
The aim and object of the invention is therefore, either a single improvement or the solution of one or more aims of the invention, singly or in combination; for example:
an increase of the cross-sectional area of the bearing faces between piston and piston shoe in order to obtain a radial strength and thereby high-pressure fluid handling capability of the device;
an increase of the radial bearing force capability of the device;
a high pressure device of at the same time high volumetric flow through capability;
an improvement of the increase of the volumetric flow through capability of a device of a given size and weight;
an increase of the piston stroke of high-pressure piston shoes in a rotor of a given diameter in a radial piston fluid handling device;
and/or the provision of a simple fluid handling device which is easy to manufacture, inexpensive or less in weight and size for a given power or stroke of fluid handling devices with piston shoes which are pivotally associated to the respective pistons of the device.
One of the aims and objects of the invention is achieved in that in a radial-piston type fluid-handling device with piston shoes which are swingably associated to pistons of the device, end wall means are provided on or associated with the rotor or piston stroke actuator means for the prevention of escape of piston shoes out of their associated spaces and the provision of a radial support member on the medial portion of the piston shoe which forms together with the associated piston bearing faces of a constant radius around a common mean, and which extends so far radially towards the piston that at least a portion of the medial support radial extension of the piston shoe remains at all times of the piston stroke between portions of the rotor or of segments or radial extensions of the rotor.
Another aim and object of the invention is achieved in that the pistons and piston shoes remain unconnected so much that they can fit together when pressure appears in the respective cylinder which forces the piston and piston shoe together for engaging each other at their bearing faces of common radius around a common mean.
The aims and objects of the invention are achieved to maintain a device of high rate of flow or volumetric capability while at the same time enabling a high radial strength of the pistons and piston shoes and thereby a capability of them to operate with fluid of very high pressure.
Another aim and object of the invention is to use a piston shoe which has a central portion which bears on its ends piston-shoe guide portions and recesses to both sides of the central portion in directions of rotation and contrary thereto and interrupting the guide portions of the piston shoes in two end portions for the reception of rotor-radial segments or portions of the rotor of the device. The rotor segments or portions may also be called rotor-radial extensions. Thus in order that the peripheral intersecting recesses are provided in the piston shoe to both sides of the medial piston shoe portion and between the end guide portions of the piston shoe, the piston shoe can enter completely into the cylinder portions of the rotor deeply beyond the outermost or innermost diameter of the rotor's radial extensions if the radial extensions of the rotor are provided and if they are narrower than the recesses or intersecting recesses of the piston shoes. This feature provides the desired large piston stroke of the device and thereby the desired large rate of flow or volumetric capacity of the device.
Another aim and object of the invention is achieved in that a large portion of the cross-sectional area of the piston is utilized for forming the bearing faces between piston and piston shoe which are pivotable on each other. Thereby great radial strength of these members is obtained. Because a bigger bearing face can exert more force and also because a cross-sectionally bigger piston shoe radial extension can bear a higher radial force and pressure than a smaller cross-sectional area radial extension. In order to obtain this aim the connection between the pistons and piston shoes is eliminated in this embodiment of the invention. A piston piston-shoe connection would need a portion of the cross-sectional area of the pistons or a respective one of the piston shoes, if one of them embraces the other. The embracing of the piston shoe portion by the piston or the embracing of the piston portion by the piston shoe, which is required in order to connect the pistons and piston shoes pivotably together by the embracing of one of the other and which takes a portion of the cross-sectional area of the piston away from the bearing faces between the pistons and piston shoes, is spared by this embodiment of the invention and thereby the area of the bearing faces between the pistons and piston shoes is increased.
Another feature of the invention is that the bearing between piston and piston shoe consists of a hollow ball-shaped recess in the top of the piston and in a substantial semi-spherical shape of the radial outer end of the radial support portion of the piston shoe. Thus three objects are achieved, namely: a simpler form of the bearing means between piston and piston shoe which can be easily and inexpensively be machined; the highest bearing capacity between piston and piston shoe by using the maximal possible extension of the cross-sectional area of the bearing faces between piston and piston shoe relative to the cross-sectional area of the piston, and finally that at least one portion of the piston shoe radial extending support portion remains within the inner radial confines of the outermost radial extension of the rotor extensions so that the maximum of possible piston stroke for high rate of flow volumetric capacity is obtained and at the same time any tangential escape of the piston shoe out of its associated space is and remains prevented.
Another feature of the invention is that at all locations during the maximum extent of the piston stroke at least a portion of the bearing face between the pistons and piston shoes remains within a portion of the cylinder or cylinder-face extension of the device.
A further aim and object of the invention is achieved in that the medial piston-shoe portion, which may also be called the piston-shoe central portion, is integral with the radial support extension of the piston shoe and with the guide portions of the piston shoe axial ends outside the intersecting recesses on both sides of the central portion extending peripherally or tangentially. This one-piece integration supplies also the needed strength for radial rigidity and thereby for radial force-transmitting capability, which results in high pressure capability for the handling of high-pressure fluid.
A still further aim and object of the invention is achieved in that the diameter of the face of the piston stroke actuator means turned toward the rotor is at least a little but greater than the diameter of the rotor at the actuator, and that the radial extension of the piston shoe is a little bit larger than the size of the piston stroke, or than 2e of the device, wherein e is the eccentricity between the axis of the rotor and the axis of the actuator means. This characteristic of this feature of the invention assures that at all times and locations the piston and piston shoe can fit into each other automatically again. This provision prevents any escape of the non-connected piston shoe out of its associated space.
Another feature of this invention is that at the ends of a space for containment of the piston shoes end walls or end faces are provided which may be attached to respective end shoulders of the rotor or of the actuator. Thereby the axial escape of the piston shoe out of this space for containing the piston shoes is prevented.
Closely related to the above is another feature of the invention which consists in that a piston shoe containment space is provided between the rotor, the actuator, and end walls of the device.
According to a further feature of the invention the end walls or end faces are extended so wide radially that they at all times embrace at least a portion of each piston shoe. Thus the piston shoes are held within the respective containment spaces between the end walls or end members.
High mechanical efficiency of the device of the invention with less friction or a minimum of friction is achieved in that a small clearance space is provided between the outermost axial ends of the piston shoes and the innermost faces of the end members, walls, or faces.
Common to all of the provisions for attaining an aim or object or aims or objects of the invention is the location of the piston shoes between the actuator means, the rotor, and end members and that at the same time at least a portion of the radial support extension member of the piston shoe is provided within a cylinder or at least between a pair of radial extensions or segments of the rotor of the device.
Another provision for attaining an aim or object of the invention consists in keeping the pistons and piston-shoes unconnected and keeping them freely movable independent of one another in order to assure an especially safe and reliable operation of the radial-piston fluid-handling device. Thus assures that the device can continue to operate even if one or more of the pistons sticks within the respective cylinder. If a piston sticks, the piston shoe can separate from the sticking piston and freely float within its associated piston-shoe containment space. Any breaking of pistons and piston-shoes, which occurred in earlier devices, is thereby prevented. In order to assure this provision for obtaining safe and reliable operation of the device, the following provisions may be applied in order to obtain the aims or objects of the invention:
the assurance that the piston shoe at all times centers itself in the respective piston-shoe seat after it has separated from the piston shoe by containing the piston shoe in the piston-shoe containment space between the actuator, rotor, and end members at the same time assuring the needed radial extension of the piston-shoe radial support member so that it remains at all times and locations between a pair of radial extensions of the rotor;
the provision of at least one-dimensional free play of the piston shoe so that the piston shoe is provided independent of the associated piston and free of it for at least one-dimensional free play, which is radial free play;
the provision of at least two-dimensional free play for the piston shoe which is free from connection to the associated piston and independently radially movable for the first dimension of free play in a radial direction and which is at least in a limited extent axially freely movable between the end members within the clearances between the ends of the piston shoes and the end members for the second dimension of free play of the piston shoe. The second dimension of free play is thereby the limited axial free play;
the provision of three dimensional free play for the piston shoe which has radial free play and the said axial free play and which has additionally the third dimension of free play which is that the piston shoe can float freely to a limited extend in the rotation direction of the rotor or contrary thereto. This direction of movement of the rotor is in this specification also called peripherally or tangentially or peripheral or tangential. This provision of the third dimension of free play is assured in that the radial support member of the piston shoe is somewhat shorter in peripheral and tangential direction than the diameter of the cylinder. Thus the radial support member of the piston shoe can freely float tangentially and peripherally between the adjacent pair of rotor radial extensions within the limit of its freedom as defined by the clearance therebetween. The floating of the radial support member between the rotor's radial extensions also makes the whole piston shoe floatable in the third dimension of free play.
The provision of one or multi-dimensional free play of the piston shoe enables rough machining tolerances of the respective parts and thereby makes the manufacturing more easy and inexpensive, while it at the same time prevents friction between closely juxtaposed moving parts, as such closeness of moving parts is not present.
Further features of the invention are: that a plurality of cylinder groups and piston groups are provided in the same rotor of the device and the piston shoes or piston and piston shoes are at least partially radially freely movable during at least a part of the piston stroke; that the piston shoes of a multipiston group device have at least small spaced or clearances between them and neighboring parts or members to prevent friction due to closeness between relatively moving parts or for the purpose of easy or inexpensive machining with rough machining tolerances or for the assuring of reliable operation of the device or for the prevention of sticking or breaking of parts of the device; that radial extensions are provided in a multipiston group device on those ends of the respective piston shoes which extend toward piston shoes of the other piston group in order to prevent the escape of piston shoes of one group into the space of the other group so that the reliability of the device and of its parts is assured;
that there is provided in the radial extensions on the respective end of the piston shoes of a multipiston group device a recess or ring groove in the rotor between the neighboring cylinder groups for the temporary reception of the radial extensions of the ends of the piston shoes, the recess or ring groove serving to make possible a large piston stroke and thereby large volumetric capacity in the device;
that end members are provided on the axial ends of the piston-shoe containment space in order to prevent an overly large axial movement of the piston shoes;
that the common radius around the common mean of the bearing faces between piston and piston shoe are of a radius which is in a limited extent larger than the radius of the associated piston in order to constitute a large bearing face with a suitable medial angle of inclination relative to the axis of the respective piston;
that the piston shoe and its radual support portion are so extended or reduced that they have such radial length or extension that they cannot escape from their associated spaces but also obtain maximum strength and withstand a maximum pressure and create a maximum rate of flow so that a maximum of pressure capability and a maximum of volumetric capability and thereby a power maximum of a device of a given size or weight possible is obtained, whereby they also may obtain a maximum of efficiency of the device while remaining secure in their respective space or locations so that at all times and locations a portion of the radial support member of the piston shoe remains between adjacent radial extensions of the rotor;
that entering piston shoes are provided in the radial-piston fluid-handling device;
that deep-diving piston shoes are provided in the radial-piston fluid-handling device;
that a maximum of pressure and/or a maximum of rate of flow is obtained in the device by securing the piston shoes by portions or a portion of each of them between adjacent pairs of rotor-radial extensions; and/or,
that means are provided, which appear in the drawings, in the description, specification or claims.
A considerable portion of the objects and aims of this invention have in the meanwhile be obtained in my grand-parental application, Ser. No. 528,346 of Nov. 29, 1974; now U.S. Pat. No. 4,037,523, which issued on July 26, 1977.
However, in the mentioned grand-parental application the piston shoes or pistons were guided on radial extensions of the rotor of the device.
In accordance with this invention, it has now however been materialized, that the common rotor without radial extensions can also be used to provide a radial piston fluid handling device like a pump or motor, when the free floating piston shoe or piston shoe assembly is properly designed and suited to be used therein. The invention therefore discloses the details of such application of the piston shoe or assembly into the common rotor which has no radial extensions for guidance of pistons or shoes.
The application also deals with modifications and improvements of portions of my mentioned patent, which issued on the grand-parental application.
Such modifications or improvements are, for example, integral end members on the rotor, forming innermost guide faces for the piston shoes; improved flow-through restriction means in the pistons and a ball-formed portion on a piston shoe of a diameter suitable to guide itself by line contact on portions of a respective cylinder wall.